Improvement in bolting screens or sieves



G. N. FORNEY 8; G. W. BANGE.

B'oltin'g Screen or Sieve.

N0. 219,242. Patented Sept. 2,1879."

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UNIT D STATES PATENT, OFFICE.

, GEORGE N. FORNEY AND GEORGE W. BANGE, OF HANOVER, PA.

IMPROVEMENT IN BOLTlNG SCREENS 0R srEvEs.

Specification forming part of Letters Patent No. 219,242, dated September 2, 1879 application filed June18, 1879.

tion, which will enable others skilled in the art to which it appertains to make and use the same, reference being hadto the accompanying d rawings, which form a part of this specification.

1n the accompanying drawings, Figure 1 represents our device attached to the frame of a bolting-screen. Fig. 2 is a vertical sectional view of the device itself from w to m. Fig. 3 is a vertical section of Fig. 2 at y y.

The same letters of reference indicate the This invention relates to an improved device for correcting automatically and immeand passing over it.

The device consists of springs attached to a cross-bar at each end in such a manner as to exert pressure in two directly opposite directions. These springs bear from within outward against the two opposite sides of the screen-frame, the two sides being curved either inward or outward, so as to be either of a concave or convex shape. Thus a stretching force is developed between these two sides which not only keeps tense the bolting-cloth attached to the frame, but which, in consequence of the sides being curved, exerts itself most where the slack is most likely to occur--t'. 0., in the middle portion of the material which is attached to the screen-frame.

The action of this device is automatic and instantaneous, inasmuch as the spring force can be utilized only as the bolting-cloth or other material stretches or sags, and is utilized or applied at the very instant when the stretch occurs without additional or special adjustment.

The axes H H are passed into the sockets at either end of the cross-bar G, and are held firmly in place by means of the terminal screws F F entering the material of which the crossbar G is, made. Within these sockets, and

around the axes H H, are coiled spiral springs D D, which press against the bearing-surfaces 0 G, attached to the curved sides A A, represented in the drawings as concaved, but which may also be curved in the opposite direction.

The action of the device is as follows: The cross-bar G has screwed into it the iron rods H H, with the springs D D coiled around them. The cross-bar is then put into the frame A A B B by inserting the projecting ends of the axes H H into the transverse holes bored midway through the sides A A, and is held in place, mainly, by a screw, at-

taching it to the stanchion I I at the point K.

The sides A A are then sprung into curve, not sawed, thus making them elastic, and the bolting-cloth E, or other material, is fastened upon them while thus curved, as well as upon the other two sides, 13 B. r

In consequence of the inward curvature of .the sides A A, which shape we prefer to an outward curve, though desiring to embrace, broadly, both curves also in this patent, the springs D. D are compressed. They exert, consequently, an outward pressure upon the sides A A of the screen-frame, by means of which a tension is communicated automatically and instantaneously to the bolting-cloth or other material attached to the frame, and which, in four-sided frames, is greatest where the slack is most likely to occur, in consequence of the two opposite sidesbeing curved.

Having thus described our invention, We In testimony that We claim the foregoing as claim as new and desire to secure by Letters our own We have hereto affixed. our signatures Patent-- in presence of two witnesses.

The above-described sieve-frame, having the GEORGE N. FORNEY. opposite-curved elastic sides A and pressure- GEORGE W. BANGE. springs 1), supported and acting within the Witnesses: frame against the sides A and b01ting-c10th L. F.1VIELSHEIMER,

E, substantially as described. S. KEEPER. 

